John Deere: Tilt Steering Mechanism

Situation

3520 Compact Utility Tractor

John Deere receives many CAD-modeled parts from suppliers that they use in the tractors they manufacture. One of these parts is a handle for the tilt steering mechanism, which for an unknown reason was not aligning properly with its gear teeth. John Deere initially inspected the part using a Coordinate Measuring Machine (CMM) and determined that the parts were defective, even though the supplier insisted they were made to spec. Nevertheless, the failure rate on the assembly line was unusually high for the tilt steering mechanism. John Deere would need to compare the entire as-built shape to the as-designed model in order to determine the real cause of the misalignment.

Solution

Colormap Inspection and Scan Data

John Deere contracted 3DScanCo to scan, inspect, and confirm the existence of defects in the handles they were receiving. 3D laser scanning quickly became the ideal choice for the project due to its ability to quickly capture warpage and variations in shape over the entire part. The high resolution data captured by the Konica Minolta VIVID 9i scanner was used to generate the accurate (within 0.002 in.) inspection reports that John Deere needed to be confident in their initial findings.

3DScanCo generated a colormap inspection and a cross section analysis by comparing the resulting scan data to the as-designed CAD data supplied by John Deere. These reports clearly showed that there were several areas of deviation between the shape of the CAD and shape of the actual part, which ultimately caused a misalignment in the field.

Results

Cross Section Analysis

The inspection reports generated by 3DScanCo provided the information and confidence in the existence of defects that John Deere needed to have their supplier make modifications to the part. After a second manufacturing cycle, John Deere was supplied with a new model handle which successfully aligned with the gear teeth, allowing for proper function of the tilt steering mechanism.

The scan and inspection data generated by 3DScanCo served not only to dramatically reduce the failure rate on the assembly line, but also in giving John Deere's engineers new ideas on how to model higher quality CAD data for future parts.

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